Longitude

[William Karlin]

 I have a small quibble with the comment on SI...

On Thu, 10 Apr 1997, Bruce Appelbaum wrote:

<snip>

>      Metric prefixes are as follows:

  <a nice list, but had to save space...>

>      
>      And to confuse things even further, the metric system is being 
>      replaced by the (sp?) Systeme Internationale (SI), which is pretty 
>      much the metric system with a bunch of different names (for famous 
>      scientists) for commonly used derived units (for instance, the unit of 
>      pressure is the Pascal, the unit of energy is the Joule, the unit of 
>      power is the Watt, the unit of force is the Newton).
>      
>      As an engineer, I have to deal with varying sets of units in my work 
>      -- some traditional (pounds, tons, gallons, feet, cubic feet, BTUs), 
>      and some metric (kilograms, Joules, meters, cubic meters).  Lots of 
>      classroom time learning the units and how to do unit conversions 
>      correctly from system to system.


   SI isn't replacing the metric system.  They are the same thing
essentially.

  The metric system (all the old favorites: the meter, liter, gram) are
the base units, and may have  one of those prefixs attached.

  The derived units (like the Newton) are aggregates of these base units.
The Newton, for example, is a (kilogram*meter/seconds^2) -- this is a unit
of force.  There are tons of others and Bruce is right it takes years to
get these things straight (I'm on my way to grad school for physics, so I
have a bit of an idea).
   However, these units are not replacing the metric system...it's not
like the 'meter' is beginning to be called the 'Feynman' or something --
at least as far as I know!  They are just built from the metric system.
It's a lot easier to call something a 'Newton' than a
'kilogram-meter-per-seconds-squared'

  sorry to drag the  list off-course for the second time in a day...


Will